A cataract is a clouding (usually gradual) of the eye's natural lens. Most adults over age 60 have symptoms of cataracts. A cataract can be the reason sharp images become blurred, or seeing things at night is more difficult. It may also be why the eyeglasses or contact lenses that used to help you read, or do other simple tasks, no longer seem to help. More than a million cataract operations will be performed nationwide this year alone.